Kinesiology Exam 1

Diarthrodial (Synovial)Joint

-Freely movable -Composed of sleevelike joint capsule -Secretes synovial fluid to lubricate joint cavity -Capsule thickenings form tough, nonelastic ligaments that provide additional support against abnormal movement or joint opening

External Levers

-Using a small force to overcome a large resistance. Ex. a crowbar -Using a large ROM to overcome a small resistance. Ex. Hitting a golf ball -Used to balance a force and a load Ex. a seesaw

Tendon Reflex

Stimulus - high level of stretch, due to muscle stretch, or muscle contraction. Receptor - GTO Response - (-) relaxation of stretched muscle and (+) facilitation of antagonist.

Postural Adaptation

Two primary strategies on a continuum: Hip strategy- -Achieved through trunk flexion/extension and hip flexion. -Focus on balance in sagittal plane. Ankle strategy -Ankle/foot adopts a position that allows stability to be maintained. -Used often for abrupt changes of support surface

Angular or Rotary Motion

Typical of levers, wheels, & axles Object acting as a radius moves about a fixed point. Measured as an angle, in degrees. Body parts move in an arc about a fixed point

Hinge joint

Uniaxial articulation Articular surfaces allow motion primarily in one plane ex. elbow, knee

Pivot Joint

Uniaxial articulation Examples: 1. Atlantoaxial (AA) jt - Odontoid turns in bony ring 2. Proximal Radio-ulnar jt

Saddle Joint

Unique triaxial joint 2 reciprocally concave & convex articular surfaces Examples: 1st CMC jt at thumb and Sternoclavicular jt

Trigonometric Resolution of Vectors

ionships of a right triangle are employed. Ex. A soccer ball is headed with an initial velocity of 9.6 m/s at an angle of 18°.

Muscle contractions (under tension)

isometric Isotonic (concentric and eccentric)

Chart from direction and point of application of external forces

memorize chart

torque

motion occurring about an axis

Muscle contraction occurs whenever...

muscle fibers generate tension May occur while muscle is shortening, remaining the same length, or lengthening.

Internal forces

muscle forces that act on various structures of the body.

Extrinsic

muscles that arise or originate outside of (proximal to) body part upon which they act Example: Forearm muscles that attach proximally on distal humerus and insert on fingers Cause fingers to move, but originates @ elbow Power

Intrinsic

muscles within or belonging solely to body part upon which they act. within hand precision

Aggregate muscle action

muscles work in groups rather than independently to achieve a given joint motion Chain Reaction

Every structure that participates in movements of the body does so according to...

physical and physiological principles

Bernoulli's Principle

pressure in a moving fluid decreases as speed increases.

Contraction

when tension is developed in a muscle as a result of a stimulus

Four types of forces that affect body motion:

1. Gravity 2. Muscles 3. Externally Applied Resistances 4. Friction

Types of Body Movement

Passive: no effort on the part of the subject involved, motion due to outside force. Active: movement is produced by the subject's own muscular activity.

Length of Moment Arm

Perpendicular distance from line of force to axis of rotation. Moment arm is no longer the length of the forearm. Can be calculated using trigonometry.

Phasic Response Application

Phasic preparatory phase can take advantage of stretch reflex. Results in stronger contraction.

Center of Gravity (COG)

"Balance point" of body Point where all forces acting on the body equal zero: -Linear forces must be balanced. -Torques must be balanced. Location of COG remains fixed as long as body does not change shape. If object's shape or position changes, location of COG changes.

Isometric contraction

"Equal length" Active tension is developed within muscle Joint angles remain constant Static contractions Significant amount of tension to maintain joint angle in relatively static or stable position Used to prevent a body segment from being moved by external forces Preventing motion

Gliding joints

-2 plane or flat bony surfaces -Little motion possible in any 1 joint articulation -Usually work together in series of articulations ex. vertebral facets in spinal column

B. Anatomical Analysis

1. Joint actions and segments motion -joints involved? -exact movements in the skill? -any limited ROM? 2. Muscle participation and form of contraction -muscles producing joint actions -type of contraction: eccentric, concentric, isometric, econcentric 3. Neuromuscular considerations -what neuromuscular mechanisms are involved? motor control..proprioception -what is the nature of involvement? 4. Anatomical principles related to effective and safe performance -which anatomical principles contribute to efficiency and accuracy? -which principles are related to avoidance of injury?

2 classifications of movement patterns

1. Linear or Translatory 2. Circular Motion or Rotary

Key Skeletal Functions

1. Protection of heart, lungs, brain, etc. 2. Support to maintain posture 3. Movement by serving as points of attachment for muscles and acting as levers 4. Mineral storage such as calcium & phosphorus

Hierarchy of Evidence

1. Systematic reviews 2. Critically Appraised topics 3. Critically appraises individual topics 4. Randomized control trials 5. cohort studies 6. Case controlled studies case reports 7. Background Information/ Expert opinion

Five variables determine and describe motion

1. Type 2. Location 3. Magnitude 4. Duration 5. Rate or motion of change

C. Mechanical Analysis

1. Underlying mechanics objective(s) a. Balance: regain stability, attain mobility **Jump stop, track start b. Locomotion: travel **Walking, running, skipping c. Projection: height, range & accuracy **Pole vault, long jump, throwing Manipulation: objects or resistance Weightlifting, writing Maximum effort: speed, power, & force Sprinting, power lift, blocking 2. Nature of forces causing or impeding motion -Internal: body mass, gravity -External: weight, another person -Modifying forces: swimming in water 3. Identifying critical elements 4. Mechanical principles that apply - concerning safety, effectiveness, efficiency

Factors that Determine the Range of a Projectile

1. Velocity at release 2. Angle of projection 3. Height of release 4. Height at landing

Muscle Fibers

2 major categories pertinent for kinesiology: Slowtwitch: Type 1 Fast twitch: Type 2 Most limb muscles contain a relatively equal distribution of each fiber type. Postural muscles contain more slow twitch fibers.

Spinal Nerves

31 pairs - exit both sides of vertebral column 8 Cervical 12 Thoracic 5 Lumbar 5 Sacral 1 Coccyx

Acceleration due to Gravity

32 ft/sec2 or 9.8 m/sec2 Velocity will increase 9.8 m/sec every second when an object is dropped from some height. End of 1 sec = 9.8 m/sec End of 2 sec = 19.6 m/sec End of 3 sec = 29.4 m/sec

Quadrate or Quadrilateral

4 sided and usually flat. Consist of parallel fibers. Example: Rhomboids

Effects of Spin on Bounce

A ball with: topspin, will rebound from horizontal surface lower and with > horizontal velocity. backspin, will rebound higher and with < horizontal velocity. no spin, will develop topspin. topspin, will gain > topspin. backspin, may be stopped or reversed.

Balance and COG

A person has balance, depending on height of COG Lower COG > more balance

Mechanical Axis of Bone

A straight line that connects midpoint of joint at one end of a bone with midpoint of joint at other end. Axis may lie outside the shaft.

Torque and Length of Lever Arm Ex.

A tennis player can hit a tennis ball harder with a straight- arm drive than with a bent elbow because the lever (including the racket) is longer & moves at a faster speed

Kinesiological Analysis

A. Description of the motor skill performance 1. Primary purpose of the skill -applicable references to speed, accuracy, form, etc. 2. Movement phases: "breakdown motion into "phases" 3. Classification of the skill: provides clues to nature of anatomical and mechanical requirements of a group of skills 4. Simultaneous-sequential nature of motion: simultaneous-sequential segments move as 1 and in an orderly sequence

Frontal plane about an AP axis

Abduction: movement away from midline. Adduction: return movement from abduction. Lateral Flexion: lateral bending of head or trunk.

Law of Acceleration

Acceleration: the rate of change in velocity A change in the acceleration of a body occurs in the same direction as the force that caused it. The change in acceleration is directly proportional to the force causing it and inversely proportional to the mass of the body

Motion

Act or process of changing place or position with respect to some reference object. At rest or in motion depends totally on the reference. Sleeping passenger in a flying airplane: -At rest in reference to the airplane. -In motion in reference to the earth

Myofilaments

Actin→when stimulated slides over myosin. Functional contractile unit of skeletal muscle

Isotonic contractions

Active tension to either cause or control joint movement -Dynamic contractions -Varying degrees of tension in muscles → joint angles changing Either concentric or eccentric on basis of whether shortening or lengthening occurs

Major problems in movement are

How to take advantage of these factors. How to minimize when detrimental to movement.

Skeletal System

Adult skeleton 206 bones Axial skeleton 80 bones Appendicular 126 bones Occasional variations

Analyzing joint motions

Alignment: optimum alignment should be based on efficiency, effectiveness, and safety. Range of Motion: ROM demands of an activity must be compatible to avoid injury. Flexibility: reduces internal resistance to motion.

Naming joint actions in complex movements

All joint actions are named as if they were occurring in anatomical position. Plane and axis are ID as those in which movement actually occurs.

Stability and Equilibrium

All objects at rest are in equilibrium. All forces acting on them are balanced. Sum of all linear forces equals zero. Sum of all torques equals zero. However, all objects at rest are not equally stable.

Magnitude

Amount of force being applied. Force exerted by the barbell Force was result of gravity acting on mass of barbell.

EMG

Amplifier of Muscles

Musculoskeletal Framework

An arrangement of bones, joints, & muscles. Acts as a lever system allowing for a great # of coordinated movements. An anatomical lever is a bone that engages in movement when force is applied to it. Force is from a muscle attached to bone or an external force (gravity or weight). Muscles can directly produce motion only by shortening.

Rotary vs. Non-rotary Components

Angle of pull < 90 deg Non-rotary force is directed toward fulcrum. Helps maintain integrity of the joint (stabilizes). Angle of pull > 90 deg Dislocating force is directed away fulcrum. Does not occur often. Muscle is @ limit of shortening range and not exerting much force. Known as: active insufficiency

Buoyancy

Archimedes'Principle: a body immersed in liquid is buoyed up by force equal to weight of liquid displaced. Explains why some things float and some things sink. Density is ratio of weight of an object to its volume.

Myofibrils

Are arranged in parallel formation. Made up of alternating dark & light bands that give muscle fiber their striated appearance

Synovial Joints

Articular or hyaline cartilage covers articular surface ends of bones inside the joint cavity -absorbs shock -protects bone Slowly absorbs synovial fluid during joint unloading or distraction Secretes synovial fluid during subsequent WBing & compression Utilizing a joint through its normal ROM is important to sustaining joint health and function. Some synovial joints have specialized fibrocartilage disks -Medial and Lateral menisci: knee -Glenoid labrum: shoulder -Acetabular labrum: hip

Active Insufficiency

As muscle shortens → ability to exert force diminishes Active insufficiency: muscle becomes shortened to point that it can not generate or maintain active tension Example: Rectus femoris contracts concentrically to both flex the hip & extend the knee Can completely perform either action one at a time but actively insufficient to obtain full range at both joints simultaneously -not as strong at end range

Force-Velocity Relationship

As speed of contraction increases, the concentric force it is able to exert decreases. At maximum velocity of contraction the load is zero.

All lever systems have each of these 3 components in one of three possible arrangements

Axis (A)- fulcrum - the point of rotation Point (F) of force application (usually muscle insertion) - effort Point (R) of resistance application (COG of lever) or (location of an external resistance)

Third Class Lever

Axis of rotation at end; force arm < resistance arm Most common in human body Designed to produce speed of distal segment Able to move small weights a long distance Occurs frequently in an open kinematic chain ex. bicep curl

Second Class Lever

Axis of rotation at end; force arm is > resistance arm. Produces force movements, since a large resistance can be moved by a relatively small force Relatively few 2nd class levers in body ex. heel lift

First Class Lever

Axis of rotation located between force and resistance arm Length of force and resistance arms vary ex. tricep extension (skull crusher)

Machines (Function in 4 ways)

Balance multiple forces Enhance force to reduce total force needed to overcome a resistance Enhance ROM & speed of movement so that resistance may be moved further or faster than applied force Alter resulting direction of the applied force

When a ball is held as the arm moves in a windmill fashion...

Ball is moving with circular motion. Arm acts as a radius moving with angular motion.

Sudden addition of weight to hand, elbow @ 90°

Biceps stretches → contracts.

Statics and Dynamics

Biomechanics includes statics & dynamics. Statics: all forces acting on a body are balanced The body is in equilibrium. Dynamics: deals with unbalanced forces Causes object to change speed or direction. Principles of work, energy, & acceleration are included in the study of dynamics

Location of motion

Body motion occurs around axes within respective planes of motion. A plane of motion is perpendicular to the axis of motion around which it rotates.

Nerves

Bundle of fibers, enclosed within a connective tissue sheath, for transmission of impulses. Typical spinal nerve consists of: Motor, outgoing (axons) fibers Sensory, incoming (dentrite) fibers

Axons

Carry impulses away from cell body

Dendrites

Carry impulses toward cell body

Cause of Motion

Cause of motion is some form of force. Force must be > object's inertia, or resistance to motion. Force relative to resistance will determine if object will move or remain at rest.

Anatomical pulleys

Change course of tendon Increase mechanical advantage by moving tendon further from axis of rotation ex. Lateral malleolus acts as a pulley around which peroneus tendon runs. As peroneus longus contracts, pulls toward its belly (toward the knee) causing force to be transmitted to plantar surface of foot → Eversion/plantar flexion of ankle

Anatomical Pulley

Changes angle of pull of muscle providing the force. Increase in angle of pull increases rotary component. -Patella for the quadriceps

General Motion

Combinations of linear & angular motion Angular motions of forearm, upper arm & legs. Hand travels linearly and imparts linear force to foil.

Long bones

Composed of a long cylindrical shaft with relatively wide, protruding ends

Action of Bi-Articulate Muscles

Concurrent Actions: Simultaneous flexion or extension of the hip and knee joints. Countercurrent Action: 1 muscle shortens at both joints as antagonist lengthens → gains tension at both ends.

how is movement of joint limited?

Configuration of the bones that form an articulation, together with the reinforcing ligaments, determine and limit the movements of the joint.

Kinesthesis

Conscious awareness of position of body parts and amount and rate of joint movement. Without rapid transmission & processing, accurately controlled movements could not proceed. Kinesthetic perception & memory are basis for voluntary movement and motor learning.

The Motor Unit

Consists of a single motor neuron and all muscle fibers its axon supplies. All muscle fibers in a motor unit are of same muscle fiber type. Vary widely in # of muscle fibers.

Uniformly Accelerated Motion

Constant acceleration. Common with freely falling objects. Air resistance is neglected. Objects will accelerate at a uniform rate due to acceleration of gravity. Object projected upward will be slowed at same uniform rate due to gravity.

Golgi Tendon Organ (GTO)

Embedded "in series" in tendon. > Tension in tendon →GTO is activated. Signals CNS to relax muscle. Protective mechanism.

Vector Quantities

Equal if magnitude & direction are equal.

Components of Analysis

Describing a skill in a logical fashion. • Breaking it down into its elements. • Determining which elements are critical to SEE principle for performance. Evaluating Performance -Identifying errors in performance -Identifying the sources of error Prescribing corrections based on appropriate Identification of cause

Analysis Under Everyday Conditions

Develop qualitative skills necessary for accurate observation, diagnosis, and treatment of faulty motor performance.

Direction

Direction of a force is along its action line. Gravity is a downward-directed vector through COG of the object. Direction of a muscular force vector is direction of line of pull of muscle.

Direction

Direction of a force is along its action line. Gravity is a downward-directed vector through the center of gravity of the object. Direction of a muscular force vector is the direction of line of pull of the muscle.

Linear Kinematics

Distance -How far an object has traveled. Displacement -Distance an object has moved from reference point.

Mechanics

Divided into Statics and Dynamics

Drag

Drag is resistance to forward motion through a fluid. Smooth surface will have > laminar flow than a rough surface, resulting in < drag.

units of measurement

Expressed in terms of space, time, and mass. U.S. system: current system in U.S. -Inches, feet, pounds, gallons, second Metric system: currently used in research. -Meter, kilogram, newton, liter, second

Range of Motion (ROM)

Factors that affect stability of a joint are also related to its ROM: 1. Shape of articular surfaces. 2. Restraining effect of ligaments. 3. Muscles and tendons Flexibility should not exceed muscle's ability to maintain integrity of joint. Additional factors include: injury or disease, gender, body build, heredity, occupation, exercise, handedness. and age.

Unipennate muscles

Fibers run obliquely from a tendon on 1 side only. Examples: biceps femoris, posterior tibialis

Size of motor units

Gastrocnemius: 2,000 > muscle fibers per motor unit. Eye muscles: may have < 10 fiber per motor unit. Small ratio of muscle fibers to motor neurons is capable of > precise movements. Size of motor unit has a direct bearing on precision of movement.

Balance, Equilibrium & Stability

General factors applicable to enhancing equilibrium, maximizing stability, & ultimately achieving balance: A person has balance when COG falls within base of support (BOS) A person has balance in the direct proportion to the size of the base > BOS → balance A person has balance depending on the weight (mass) > weight → > balance

Analysis of linear movement

First ID nature of forces involved in the motion of interest: -Weight -Propulsive forces -Ground Reaction Force -Friction -Buoyancy, Drag, & Lift

Sagittal plane about a M-L axis

Flexion: Examples: -Tipping head forward -Raising entire lower extremity forward-upwardas though kicking -Raising forearm straight forward -Elbow straight, raising entire (UE) upper extremity forward-upward

Angle of rebound

For a perfectly elastic object, the angle of incidence (striking) is equal to the angle of reflection (rebound).

Contact Forces: Normal Reaction

For every action there is an equal and opposite reaction. Jumper pushes off ground and ground pushes back.

Law of Reaction (3rd Law)

For every action there is an opposite and equal reaction As we place force on a surface by walking over it, the surface provides an equal resistance back in the opposite direction to the soles of our feet Force of the surface reacting to the force we place on it is ground reaction force Our feet push down & back, while the surface pushes up & forward Easier to run on hard track than on sandy beach due to difference in ground reaction forces of 2 surfaces

Effect of Muscle Structure on Force

Force a muscle can exert is proportional to its physiological cross section (PCS). A broad, thick, longitudinal muscle exerts more force than a thin one. A pennate muscle of the same thickness as a longitudinal muscle can exert greater force. Oblique arrangement of fiber allows for > # of fibers than in comparable sizes of other classifications.

Torque and length of lever arms (force and resistance)

Force arm - perpendicular distance between location of force application & axis Resistance arm - distance between axis and point of resistance application

Summation of Forces

Force generated by muscle may be summated from one segment to another. Typical throwing pattern: -Force from legs is transferred to trunk. -Further muscular force increases momentum and is transferred to upper arm. -Mainly as an increase velocity because mass is smaller. -Sequential transfer of momentum continues with mass decreasing and velocity increasing. Finally, momentum is transferred to thrown ball.

Force

Force is a vector quantity: Magnitude and direction Also has a point of application

Torque and length of lever arms

Force is applied where a muscle inserts on bone, not in belly of muscle Human leverage system is built for speed & range of movement at expense of force Often, purposely increase force arm length in order to increase torque so can more easily move a relatively large resistance (increasing our leverage) or decrease to protect an injured joint/muscle. Short force arms & long resistance arms require great muscular strength to produce movement The longer the force arm, the less force required to move the lever if the resistance & resistance arm remain constant Long levers produce more linear force and thus better performance in some sports such as baseball, hockey, golf, field hockey, etc.

Parallel Forces

Forces not in the same action line, but parallel to each other. Three parallel forces: 1. two upward 2. gravity and mass (weight)

Internal or anatomical factors modifying motion

Friction in joints Tension of antagonists, ligaments & fasciae Anomalies of bone & joint structure Atmospheric pressure inside joints Interfering soft tissues.

Contact Forces: Friction

Friction is force that opposes efforts to slide or roll one body over another. Amount of friction depends on nature of surfaces and forces pressing them together. Friction is proportional to the force pressing two surfaces together.

External Factors Modifying Motion

Friction: helps a runner gain traction, but hinders rolling of a ball. Air Resistance: or wind is indispensable to sailboat's motion, but may impede a runner. Water Resistance: is essential for propulsion, yet it hinders an objects' progress through water.

Segmental Alignment

Human body consists of a series of segments placed one above the other. Challenge of retaining equilibrium is a multiple one. When segments are aligned in a single vertical line, there is less strain to joints and muscles. When one segment gets out of line, another segment must compensate for it.

The nervous system and basic nerve structure

I. Central nervous system A. Brain B. Spinal cord II. Peripheral nervous system A. Cranial nerves (12 pairs) B. Spinal nerves (31 pairs) III. Autonomic nervous system A. Sympathetic B. Parasympthetic

Angle of Attachment

If shallow→tension will produce a force pulling along bone. → >stability If large→> rotary component of force. In many muscles angle changes throughout ROM. At a 90 degree angle to bone -Most efficient at producing joint motion. -Joint capsule and ligaments provide static stability, muscles and tendons dynamic stability

All-or-None Principle

If stimulus is of threshold value, all muscle fibers of motor unit will contract.

Examples of Newton's 2nd Law

If you use same force to push a truck and push a car, the car will have more acceleration than truck, because car has less mass. It is easier to push an empty shopping cart than a full one, because full shopping cart has more mass than empty one. More force is required to push full shopping cart.

Magnitude of Muscle Force

In direct proportion to # & size of fibers contracting in a muscle. Muscles normally act in groups whose force or strength is measured collectively. Maximum muscular strength can be measured by a dynamometer. -Measures force applied by a group of muscle through an anatomical lever.

Irregular bones

Include bones throughout entire spine & ischium, pubis, & maxilla

D. Prescriptions for improvement of performance

Indicate how performance should be changed so that principles are no longer violated. Strategy for effecting change Concentrate on causes of error, not on symptoms

Law of Inertia

Inertia: resistance to action or change A body in motion tends to remain in motion at the same speed in a straight line unless acted on by a force; a body at rest tends to remain at rest The > object's mass→ > inertia Examples: Sprinter in starting blocks must apply considerable force to overcome his resting inertia -Thrown or struck balls require force to stop them

Reducing ability to exert force

Isolate gluteus maximus by maximally shortening hamstrings with knee flexion

Kinematics and Kinetics

Kinematics: geometry of motion Describes time, displacement, velocity, & acceleration. Motion may be in straight line or rotating. Kinetics: forces that produce or change motion. Linear - motion in a line Angular - motion around an axis

Coefficient of friction

Large coefficient surfaces cling together. Small coefficient surfaces slide easily. Coefficient of 0.0 = frictionless surface

Levers

Levers rotate about an axis as a result of force (effort, E) being applied to cause its movement against a resistance or weight

Types of Movement

Linear movement: when body is acted on by force of gravity or a linear external force. General Motion Rotart Motion Curvilinear Reciprocating: back and forth in straight line (cutting with a saw)

Pacinian Corpuscles

Located around joint capsules, ligament, and tendons sheaths. Activated by joint angle changes & pressure. Transmits impulses for very brief time.

Ruffini Endings

Located in deep layers of skin and joint capsule. Activated by mechanical deformation. Stimulated strongly by sudden joint movement. Sense joint position and changes in joint angle.

Muscle Spindles

Located in muscle belly, parallel with fibers. When stretched, sensory nerve →impulses to CNS, which activates motor neurons facilitating contraction of same muscle. > spindles are located in muscles controlling precise movements Sensitive to change of velocity Sharp decline in impulses with static length change. Respond to static muscle length. Impulses directly proportional to change in length.

Placement of center of gravity in humans

Location of COG of a human in standing position varies with body build, age, and gender. Female's COG is ~ 55% of standing height Male's COG is ~ 57% of standing height

Types of bones

Long bones - fibula, humerus Short bones - carpals, tarsals Flat bones - skull, scapula Irregular bones - sacrum Sesamoid bones- patella

Bipennate muscle

Long central tendon with fibers extending diagonally in pairs from either side of tendon. Example: rectus femoris

Bone Properties

Longitudinal growth continues as long as epiphyseal plates are open Shortly after adolescence, plates disappear & close Most close by age 18, but some may be present until 25 Growth in diameter continues throughout life Bone mass increases over time with increased stress Bone size & shape influenced by direction & magnitude of forces that are regularly applied Collagen provides some flexibility & strength in resisting tension Aging causes progressive loss of collagen & increases brittleness

Longitudinal

Longitudinal: long, strap like muscle with fibers in parallel to its long axis. More uniform in diameter with essentially all fibers arranged in long parallel manner Enables a focusing of power onto small, bony targets Example: Sartorius

Forces act on a mass

Mass = amount of matter in an object Affects speed & acceleration in physical movements > force is required from muscles to accelerate a 230-pound man than to accelerate a 130-pound man to the same running speed Baseball may be accelerated > a shot because of difference in weight

Muscle Length-Tension Relationship

Maximal ability to develop tension & exert force varies Dependent upon length of muscle during contraction Depending upon muscle involved Greatest amount of tension can be developed when stretched between 100-130% of resting length Stretch > 100-130% of resting length significantly decreases amount of force muscle can exert Proportional decrease in ability to develop tension occurs as a muscle is shortened When shortened to around 50-60% of resting length ability to develop contractile tension is essentially reduced to 0.

Methods of Assessing Joint ROM

Measure degrees from starting position to its maximal movement. Goniometer: axis placed directly over center of joint, one arm held stationary, other arm held to moving segment Videotape: joint centers are marked to be visible in projected image. Joint angles can be taken from images.

axes of motion

Medial-Lateral (ML): axis passes horizontally from side to side; perpendicular to sagittal plane. Anteroposterior (AP): axis passes horizontally from front to back; perpendicular to frontal plane. Vertical: axis is perpendicular to the ground and transverse plane. Rotation occurs in a plane and around an axis. Axis of movement is always at right angles to plane in which it occurs.

Cutaneous Receptors

Meissner corpuscles: touch Pacinian corpuscles: Pressure Free nerve endings: Pain

Mobility

Mobility & stability have an inverse relationship. Critical point is change from a position of stability to a state of mobility & vice versa. To initiate a step, line of gravity must be shifted forward of BOS. Swing leg then moves forward to re-establish a BOS. Often in sport, it is necessary to alter stability intentionally to become mobile. Ability to start, stop, or change direction quickly depends on manipulating stability of body. Both needed speed and direction are used to determine change in stability required to initiate motion. To enhance speed of a start, the line of gravity should be as close as possible to edge of BOS. A quick stop requires a large BOS, lower COG, and movement of line of gravity away from leading edge of the BOS.

Motion of the Body

Most joints are axial. Segments undergo primarily angular motion. Slight translatory motion in gliding joints.

Linear or Translatory

Motion in which all parts of a moving body or object move uniformly in same line or direction. Rectilinear: Straight-line progression Curvilinear: Curved translator movement

Cerebral Cortex

Motor cortex (movement) Sensory cortex (sensations)

reciprocal inhibition

Motor neurons→transmit impulses to agonist→antagonistic are simultaneously & reciprocally inhibited. Antagonists remain relaxed & agonists contract without opposition. Automatic in reflexes & familiar movements.

Skeletal Muscle Function - Line of Pull

Movement contracting muscle produces is determined by 2 factors: -Type of joint that is spans -Relation of muscle's line of pull to the joint Pectoralis major (clavicular) is primarily a flexor, but it also adducts humerus. When arm is abducted, line of pull moves above axis of rotation and contributes to abduction of humerus.

Influence of Gravity

Movements may be in direction as gravitational forces (downward), opposing gravity (upward), or perpendicular to gravity (horizontal). Horizontal motion: not affected by gravity. Lifting against gravity requires a concentric contraction of the agonist. Slowly lowering with gravity requires an eccentric contraction of the same muscle. Forceful downward motion uses agonist muscles in a concentric contraction, since gravitational pull is being exceeded.

Ball & Socket

Multiaxial or triaxial ball & socket joint Bony rounded head fitting into a concave articular surface Ex. hip and shoulder joint Motions are flexion, extension, abduction, adduction, diagonal abduction & adduction, rotation, and circumduction

Angle of Pull

Muscle angle of pull: the angle between the line of pull and the mechanical axis of the bone. A muscle's angle of pull changes with every degree of joint motion. Most resting muscles have an angle of pull <90 degrees.

Effect of Muscle Structure on ROM

Muscle can shorten to approximately half its resting length. Long muscles (fibers longitudinally arranged) along long axis can exert force over a longer distance. Pennate muscles (oblique fiber arrangement) and short fibers, can exert superior force through a short range.

Shapes of Muscles and Fiber Arrangement

Muscles have different shapes & fiber arrangement Shape & fiber arrangement affects -Muscle's ability to exert force -Range through which it can effectively exert force onto bones 2 major types of fiber arrangements -Parallel & Pennate -Further subdivided according to shape

Bi-Articulate Muscles

Muscles that pass over and act on 2 joints Whether muscles flex joints in same direction or opposite directions, not long enough to permit complete movement in both joints at same time. ex. hamstring and gastrocnemius (not weight bearing)

Muscle Arrangement

Muscles that span joints aid in stability. Especially when bony structure contributes little to stability. Example: glenohumeral joint

Machines found in the body

Musculoskeletal system may be thought of as a series of simple machines Machines - used to increase mechanical advantage Musculoskeletal system arrangement provides for 3 types of machines in producing movement Levers (most common) Wheel-axles Pulleys

Principle of Torques

Must consider both magnitude and direction Clockwise torques are traditionally considered (-) Counterclockwise torques are traditionally considered(+)

Anatomical Levers

Nearly every bone is a lever The joint is the fulcrum Contracting muscles are the force

Laws of Motion

Newton's laws of motion have many applications to physical education activities and sports

Selection of Levers

Not always desirable to choose longest lever arm. Short levers enhance angular velocity, while sacrificing linear speed and range of motion. Strength needed to maintain angular velocity increases as lever lengthens.

Projectiles

Objects given an initial velocity and released. Gravity is the only influence after release. Maximum horizontal displacement -long jumper, shot-putter Maximum vertical displacement -high jumper, pole vault Maximum accuracy -shooting in basketball or soccer Follow a predictable path -Slow upward motion, Increase downward motion, at 9.8 m/sec2.

Elasticity and Rebound

Objects rebound in a predictable manner. Nature of rebound is governed by: -Elasticity -Mass -Velocity of rebounding surface -Friction between surfaces -Angle of contact.

Force Couples

Occur when 2 or > forces are pulling in different directions on an object, causing object to rotate about its axis Coupling of muscular forces together in the body can result in a more efficient movement Common in shoulder girdle

coactivation

Occurs when there is uncertainty of movement Also occurs to maintain joint stiffness. Practice increases familiarity, and coactivation decreases→Reciprocal inhibition Efficiency of movement increases.

Passive Insufficiency

Opposing muscle becomes stretched to point where it can no longer lengthen & allow movement Hamstrings can not (usually) stretch to allow both maximal hip flexion & maximal knee extension due passive insufficiency

Length-Tension Relationship

Optimum length: length at which a muscle can exert maximum tension. Slightly > resting length. 1. Passively stretched 2. Total tension 3. Developed tension

Origin, Insertion, Belly

Origin: usually more proximal Insertion: usually more distal Contraction produces equal force on 2 attachments. -Origin usually stabilized by other muscles. Belly: central, fleshy portion of the muscle; contractile portion of muscle

Skeletal Muscle (#'s)

Over 600 skeletal muscles Comprise approximately 40-50% of body weight (BW)

Point of Application

Point at which force is applied to an object. For muscular force, this point is assumed to be muscle's attachment to a bony lever. Point of intersection of line of force and mechanical axis of the bone.

Center of gravity and posture

Posture implies shape or configuration of the body Multi-segmented human body does not have a single posture Dynamic posture is of > concern than static posture All posture is somewhat dynamic

Controlled Laboratory Studies

Primarily qualitative in beginning. Advanced studies include EMG, motion capture, force transducers & computer analysis equipment. Technology advances (2012), new abilities increase depth of knowledge and understanding.

Bone Landmarks

Processes - bony projections Processes for attachment of ligaments, muscles or tendons Processes that form joints -Condyle -Facet -Head

Acceleration

Rate of change in velocity. May be positive or negative. If acceleration is (+) → velocity will increase If acceleration is (-) → velocity will decrease Average acceleration = final velocity - initial velocity divided by time

Specific gravity

Ratio of the density of an object to density of water. An object the same weight for volume as water has a specific gravity of 1.0 An object with specific gravity > 1.0 will sink. < 1.0 float.

Stretch Reflex

Reflex contraction of stretched muscle and synergists and relaxation of antagonists. Phasic Response: Stimulus - high velocity stretch. Response - facilitates proportional contraction of stretched muscle. Ex. knee jerk (patella reflex)

Sensory Receptors

Respond to different stimuli Exteroceptors: near body surface, stimuli from outside the body. Interoceptors: sense heat, cold, pain and pressure.

Skeletal Muscle Function

Responsible for movement of body and the joints Muscle contraction produces force that causes joint movement Muscles also provide: -protection -posture and support -produce a major portion or total body heat

Transvers about a horizontal axis

Rotation Left & Right: rotation of head, neck, or pelvis. Internal & External (Lateral & Medial) Rotation: rotation of thigh and upper arm. Supination & Pronation: rotation of forearm along long axis.

Balance, Equilibrium & Stability cont.

Rotation about an axis aids balance A moving bike is easier to balance than a stationary bike

Underlying aim of kinesiology is:

SEE Principle

Proprioceptors

Stimulated by body movements. Transmit information to CNS. Two primary categories: -Muscle receptors -Joint & skin receptors

SEE Principle

Safety: structure movements to avoid doing harm to body. Effectiveness: success or failure of meeting goals of performance. Efficiency: striving to achieve movement goal with least amount of effort.

Multipennate muscles

Several tendons are present, with fibers running diagonally between. Example: deltoid

Pennate

Shorter fibers Arranged obliquely to tendons (similar to a feather) Arrangement increases cross sectional area (CSA) of muscle→increasing power Categorized based upon arrangement between fibers & tendon: -Unipennate -Bipennate -Multipennate

Co-contraction

Simultaneous contraction of movers and antagonists. Neutralizers and stabilizers may need to co-contract to counteract additional function of a mover.

Neurons

Single nerve cell consists of cell body and one or more projections.

Sensory Neurons

Situated in a dorsal root ganglion outside spinal cord Long peripheral fiber comes from a receptor

Motor Neurons

Situated in anterior horns of spinal cord Each terminal branch ends at motor end plate of a single muscle fiber

Muscle Tissue Properties

Skeletal muscle tissue has 4 properties related to its ability to produce force & movement about joint 1. Irritability or excitability - property of muscle being sensitive or responsive to chemical, electrical, or mechanical stimuli 2. Contractility - ability of muscle to contract & develop tension or internal force against resistance when stimulated 3. Extensibility - ability of muscle to be passively stretched beyond its normal resting length 4. Elasticity - ability of muscle to return to its original length following stretching

Examples of Newton's 1st Law

Slide a hockey puck on ice, eventually it will stop, because of friction on the ice. -It will also stop if it hits something, like a player's stick or a goalpost. Ball kicked in space, would keep going forever, because there is no gravity, friction or air resistance going against it. -Will only stop going in one direction if it hits something like a meteorite or reaches gravity field of another planet

Tonic Response Application

Slow preparatory phase should be used when desired outcome is accuracy. Results in low level, sustained contraction

Eccentric or Lengthening Contraction

Slowly lengthens, gives in to external force that is > contractile force it is exerting. Muscle is acting as a "brake".

Sesamoid bones

Small bones embedded within tendon of a musculotendinous unit Provide protection & improve mechanical advantage of musculotendinous units • Patella • 1st metatarsophalangeal • 1st metacarpophalangeal

Short bones

Small, cubical shaped, solid bones that usually have a proportionally large articular surface Allows articulation with > one bone

Circular Motion or rotary

Special form of curvilinear motion. Object moves along circumference of circle, a curved path of constant radius. If force stops acting on object → will move in a linear path tangent to direction of movement when released.

Reflex Movement

Specific pattern of response without volition from cerebrum. Stimulus - Receptor organ - sensory neuron - Motor neuron - muscle response

Speed

Speed is how fast an object is moving, without regard to direction of movement. Average Speed = distance traveled divided by time

Fusiform

Spindle-shaped with a central belly that tapers to tendons on each end Allows focus of power onto small, bony targets Examples: brachial, biceps brachii

Increasing ability to exert force

Squat slightly to stretch calf & quadriceps before contracting same muscles concentrically to jump

Ligaments

Strong, flexible, stress- resistant, somewhat elastic, fibrous tissues that form bands or cords. Join bone to bone. Help maintain relationship of bones. Check movement at normal limits of joint. Resist movements for which joint is not constructed. Will stretch when subject to prolonged stress. Once stretched →function is affected

Articulations-function

Structure and function of joints are interrelated Difficult to discuss them separately. Function of joints is to provide a means of moving or being moved. Secondary functions -Provide stability without interfering with desired motions. -All joints do not have same degree of stability.

Kinesiology

Study of human movement from the point of view of the physical sciences

Biomechanics

Study of mechanics limited to living things, especially the human body. Interdisciplinary science based on fundamentals of physical and life sciences. Basic laws governing effect that forces have on state of rest or motion of humans.

Mechanics

Study that answers the questions, in reference to forces and motion What is happening? Why is it happening? To what extent is it happening? Deals with force, matter, space & time. All motion is subject to laws and principles of force and motion.

Summation of Torques

Sum of 2 or > torques may result in no motion, linear motion, or rotary motion. Parallel forces applied in same direction on opposite sides of center of rotation. Example: balanced seesaw If equal parallel forces are adequate to overcome resistance, linear motion will occur. Ex. paddlers in a canoe

The 3 Laws of Motion are

The Law of Inertia The Law of Acceleration The Law of Reaction

Value of vector analysis

The ability to understand and manipulate the variables of motion (both vector and scalar quantities) will improve one's understanding of motion and the forces causing it. The effect that a muscle's angle of pull has on the force available for moving a limb is better understood when it is subjected to vector resolution. The same principles may be applied to any motion such as projectiles

Gradations in strength of muscular contractions

The same muscles contract with various gradations of strength. How do they adjust to such extremes? # of motor units activated. Frequency of stimulation

Action Potentials

Threshold level is minimum level of stimulus (chemical transmitter) necessary to initiate or propagate a signal. Facilitation: an excitatory stimulus Inhibition: an inhibitory stimulus

Relationship of Line of gravity to base of support (BOS)

To maintain equilibrium, line of gravity must remain within BOS Note hyper-extended trunk to maintain line of gravity within BOS.

Flat bones

Usually have a curved surface & vary from thick where tendons attach to very thick

Vector representation

Vector is represented by an arrow Length is proportional to magnitude

Resolution of Vectors

Vector may be broken down into 2 component vectors acting @ right angles to each other. Arrow in figure represents velocity of the shot.

Velocity

Velocity involves direction as well as speed. Speed in a given direction Rate of displacement Average Velocity = displacement divided by time

Rate and change of motion

Velocity—rate at which motion occurs -Translatory— meters/sec -Rotary— degrees/sec (decrease the radius, increase velocity) Acceleration—rate at which velocity changes -Positive—moving faster Negative—slowing down

Fluid Forces

Water and air are both fluids and as such are subject to many of the same laws and principles. Forces of buoyancy, drag, and lift apply have considerable effect on movements of human body.

External forces

Weight, gravity, air or water resistance, friction, or forces of other objects acting

Unstable Equilibrium

When a slight disturbance will drop objects' COG to a lower point.

Muscle Force - Velocity Relationship

When muscle is contracting (concentrically or eccentrically) rate of length change is significantly related to amount of force potential When contracting concentrically against a light resistance muscle is able to contract at a high velocity As resistance increases, the maximal velocity at which muscle is able to contract decreases As load increases, velocity decreases to zero → isometric contraction As load increases beyond muscle's ability to maintain an isometric contraction, muscle begins to lengthen → eccentric contraction Slight increases in load →relatively low velocity of lengthening As load increases further, velocity of lengthening will increase Load may increase to point where muscle can no longer resist→uncontrollable lengthening or dropping of load Inverse relationship between concentric velocity & force production As force needed to cause movement of an object increases the velocity of concentric contraction decreases Somewhat proportional relationship between eccentric velocity & force production As force needed to control an object's movement increases, the velocity of eccentric lengthening increases, at least until when control is lost Both muscle and tendon possess elastic properties. Concentric contraction is preceded by a phase of active stretching → Elastic energy stored in stretch phase is available for use in contractile phase. Enhanced potential for work →Combination of the series elastic components (SEC), parallel elastic components, and stretch reflex decelleration: eccentric muscle action (quad in lowering of squat) accelerate: concentric muscle action ammortization phase: in between phase, not be long, wont get the effects

Concentric or Shortening Contraction

When tension by the muscle is sufficient to overcome a resistance and move the body segment. The muscle shortens.

Angle of Pull

Y component is perpendicular to lever, called rotary component. X component is parallel to lever and is non-rotary component. REPEAT: Most resting muscles have an angle of pull < 90o. Rotary component

Sarcomere

a structural unit of a myofibril in striated muscle, consisting of a dark band and the nearer half of each adjacent pale band.

Time

basic unit in both systems in second

Mechanics, Anatomy, Physiology..... to

biomechanics, musculoskeletal anatomy, neuromuscular

Muscles attach to bone by...

connective tissue, which continues to bend the muscle belly to form a tendon

Muscle contractions can be used to

cause, control, or prevent joint movement. Initiate or accelerate movement of a body segment Slow down or decelerate movement of a body segment Prevent movement of a body segment by external forces

Synergists

cooperative muscle function Essential in establishing relatively firm base for more distal joints to work from when carrying out movements Stabilizing, Fixator, & Support Muscles Neutralizers - prevent undesired action Ex. Rhomboids stabilize scapula against pull of Teres major

Motor unit recruitment

has an orderly sequence.

Movers or Agonists

directly responsible for producing a movement. Cause joint motion through a specified plane of motion when contracting concentrically Prime movers: large impact on movement Assistant movers: only help when needed

Strain

distortion that occurs

Antagonists

effect opposite of agonists. First: Antagonists must relax to permit movement. Second: Acts as a brake at completion of movement. -Located on opposite side of joint from agonist -Have opposite concentric action Example: In standing, quadriceps muscles are antagonists to hamstrings in knee flexion

Triangular

fibers radiate from a narrow attachment at one end to a broad attachment at the other. Fan-shaped Originate from broad area & converge onto a tendon Examples: pectorals major, trapezius

Stress

force that acts to distort

Fundamental vs Anatomical standing position

fundamental has palms faced inward towards body

Recruitment

has an orderly sequence Smaller slow twitch fibers are recruited first. -Lower thresholds Larger fast twitch fibers are recruited later. -Higher thresholds

Center of gravity and line of gravity

imaginary point representing the weight center of an object Location: approx s2 Line of Gravity: imaginary vertical line that passes through the center of gravity

Weight

product of mass and gravity

Mass

quantity of matter a body contains

For quickness, it is desirable to have a

short lever arm Baseball catcher brings hand back to ear to secure a quick throw Sprinter shortens his knee lever through flexion

Mechanical Axis

straight line that connects midpoint of joints at either end of bone. Not necessarily the long axis of bone. Varus: "Bowlegged"-axis more medial Valgus: "Knock-kneed"-more lateral

Dynamics

study of systems in motion with acceleration System in acceleration is unbalanced due to unequal forces acting on the body

Statics

systems in constant state of motion, whether at rest with no motion or moving at a constant velocity without acceleration Involves all forces acting on body being in balance resulting in body being in equilibrium

Stress may take form of:

tension compression bending torsion

Force

the product of mass times acceleration Metric: newton (N) is unit of force US: pound (lb) is basic unit force

Muscle Innervation

the stimulation of a muscle by an impulse transmitted by a motor nerve